// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef NET_SOCKET_SOCKS_CLIENT_SOCKET_H_
#define NET_SOCKET_SOCKS_CLIENT_SOCKET_H_

#include <stddef.h>
#include <stdint.h>

#include <memory>
#include <string>

#include "base/gtest_prod_util.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "net/base/address_list.h"
#include "net/base/completion_callback.h"
#include "net/base/net_errors.h"
#include "net/dns/host_resolver.h"
#include "net/dns/single_request_host_resolver.h"
#include "net/log/net_log.h"
#include "net/socket/stream_socket.h"

namespace net {

class ClientSocketHandle;
class BoundNetLog;

// The SOCKS client socket implementation
class NET_EXPORT_PRIVATE SOCKSClientSocket : public StreamSocket {
public:
    // |req_info| contains the hostname and port to which the socket above will
    // communicate to via the socks layer. For testing the referrer is optional.
    SOCKSClientSocket(std::unique_ptr<ClientSocketHandle> transport_socket,
        const HostResolver::RequestInfo& req_info,
        RequestPriority priority,
        HostResolver* host_resolver);

    // On destruction Disconnect() is called.
    ~SOCKSClientSocket() override;

    // StreamSocket implementation.

    // Does the SOCKS handshake and completes the protocol.
    int Connect(const CompletionCallback& callback) override;
    void Disconnect() override;
    bool IsConnected() const override;
    bool IsConnectedAndIdle() const override;
    const BoundNetLog& NetLog() const override;
    void SetSubresourceSpeculation() override;
    void SetOmniboxSpeculation() override;
    bool WasEverUsed() const override;
    bool WasNpnNegotiated() const override;
    NextProto GetNegotiatedProtocol() const override;
    bool GetSSLInfo(SSLInfo* ssl_info) override;
    void GetConnectionAttempts(ConnectionAttempts* out) const override;
    void ClearConnectionAttempts() override { }
    void AddConnectionAttempts(const ConnectionAttempts& attempts) override { }
    int64_t GetTotalReceivedBytes() const override;

    // Socket implementation.
    int Read(IOBuffer* buf,
        int buf_len,
        const CompletionCallback& callback) override;
    int Write(IOBuffer* buf,
        int buf_len,
        const CompletionCallback& callback) override;

    int SetReceiveBufferSize(int32_t size) override;
    int SetSendBufferSize(int32_t size) override;

    int GetPeerAddress(IPEndPoint* address) const override;
    int GetLocalAddress(IPEndPoint* address) const override;

private:
    FRIEND_TEST_ALL_PREFIXES(SOCKSClientSocketTest, CompleteHandshake);
    FRIEND_TEST_ALL_PREFIXES(SOCKSClientSocketTest, SOCKS4AFailedDNS);
    FRIEND_TEST_ALL_PREFIXES(SOCKSClientSocketTest, SOCKS4AIfDomainInIPv6);

    enum State {
        STATE_RESOLVE_HOST,
        STATE_RESOLVE_HOST_COMPLETE,
        STATE_HANDSHAKE_WRITE,
        STATE_HANDSHAKE_WRITE_COMPLETE,
        STATE_HANDSHAKE_READ,
        STATE_HANDSHAKE_READ_COMPLETE,
        STATE_NONE,
    };

    void DoCallback(int result);
    void OnIOComplete(int result);
    void OnReadWriteComplete(const CompletionCallback& callback, int result);

    int DoLoop(int last_io_result);
    int DoResolveHost();
    int DoResolveHostComplete(int result);
    int DoHandshakeRead();
    int DoHandshakeReadComplete(int result);
    int DoHandshakeWrite();
    int DoHandshakeWriteComplete(int result);

    const std::string BuildHandshakeWriteBuffer() const;

    // Stores the underlying socket.
    std::unique_ptr<ClientSocketHandle> transport_;

    State next_state_;

    // Stores the callbacks to the layer above, called on completing Connect().
    CompletionCallback user_callback_;

    // This IOBuffer is used by the class to read and write
    // SOCKS handshake data. The length contains the expected size to
    // read or write.
    scoped_refptr<IOBuffer> handshake_buf_;

    // While writing, this buffer stores the complete write handshake data.
    // While reading, it stores the handshake information received so far.
    std::string buffer_;

    // This becomes true when the SOCKS handshake has completed and the
    // overlying connection is free to communicate.
    bool completed_handshake_;

    // These contain the bytes sent / received by the SOCKS handshake.
    size_t bytes_sent_;
    size_t bytes_received_;

    // This becomes true when the socket is used to send or receive data.
    bool was_ever_used_;

    // Used to resolve the hostname to which the SOCKS proxy will connect.
    SingleRequestHostResolver host_resolver_;
    AddressList addresses_;
    HostResolver::RequestInfo host_request_info_;
    RequestPriority priority_;

    BoundNetLog net_log_;

    DISALLOW_COPY_AND_ASSIGN(SOCKSClientSocket);
};

} // namespace net

#endif // NET_SOCKET_SOCKS_CLIENT_SOCKET_H_
